This paper analyzes and discusses the speed setting of high-orbit satellite measurement double-density magnetic recorders in terms of accuracy and record integrity. The basic working principle of the magnetic head is elaborated, the frequency response curve of the magnetic head is drawn, the calculation formula of the gap loss is given, and the gap loss of the playback head is the main reason for the limitation of the frequency response range of the magnetic recording. Finally, according to the relationship between the belt speed, the recording frequency and the optimal recording wavelength, the optimal belt speed setting of the high-orbit satellite is calculated and finally the basic principles of the belt speed setting are proposed.